How to make your own lightweight valve spring retainers

As the title says, lightweight retainers.
Seen on this blog before because I made them for my oldschool SS50 engine and my earlier C110 engine.
Now I'm rebuilding the original C110 engine that belongs under my C110, also with 60cc so I can keep up with modern traffic, and some more racing tricks, like lightweight retainers.

step 1:

Mount the retainers to a piece of perforated sheetmetal and spraypaint the other side.

step 2:

You now have the pattern of what to grind away, start grinding. I've used a 1mm cutting disc on an anglegrinder mounted in the vice, holding the retainers in vicegrips.

weight before:

weight after:

disclaimer: my scales ar not that accurate, when measured seperately one piece weighs 4 gramms and lightened 3 gramms.
So let's say you can achieve a 25-30% reduction in weight.
No titanium, but it only costs you some time and a little effort, no money.

And this is what it looks like, mounted in a C110 head

Maybe I should get some seethrough valvecovers...